Analog and digital signals are used to transmit information, usually through electric signals. In both these technologies, the information, such as any audio or video, is transformed into electric signals. The difference between analog and digital technologies is that in analog technology, information is translated into electric pulses of varying amplitude. In digital technology, translation of information is into binary format (zero or one) where each bit is representative of two distinct amplitudes.
An Analog signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are meaningful.
Analog Signal Vs Digital Signal Pdf Download
A digital signal uses discrete (discontinuous) values. By contrast, non-digital (or analog) systems use a continuous range of values to represent information. Although digital representations are discrete, the information represented can be either discrete, such as numbers or letters, or continuous, such as sounds, images, and other measurements of continuous systems.
Many devices come with built in translation facilities from analog to digital. Microphones and speaker are perfect examples of analog devices. Analog technology is cheaper but there is a limitation of size of data that can be transmitted at a given time.
Digital devices translate and reassemble data and in the process are more prone to loss of quality as compared to analog devices. Computer advancement has enabled use of error detection and error correction techniques to remove disturbances artificially from digital signals and improve quality.
Analog technology comprises of natural signals like human speech. With digital technology this human speech can be saved and stored in a computer. Thus digital technology opens up the horizon for endless possible uses.
A signal is an electromagnetic or electrical current that carries data from one system or network to another. In electronics, a signal is often a time-varying voltage that is also an electromagnetic wave carrying information, though it can take on other forms, such as current. There are two main types of signals used in electronics: analog and digital signals. This article discusses the corresponding characteristics, uses, advantages and disadvantages, and typical applications of analog vs. digital signals.
A digital signal is a signal that represents data as a sequence of discrete values. A digital signal can only take on one value from a finite set of possible values at a given time. With digital signals, the physical quantity representing the information can be many things:
Digital signals are used in all digital electronics, including computing equipment and data transmission devices. When plotted on a voltage vs. time graph, digital signals are one of two values, and are usually between 0V and VCC (usually 1.8V, 3.3V, or 5V) (see Figure 2).
Analog circuits can be complex designs with multiple components, or they can be simple, such as two resistors that form a voltage divider. In general, analog circuits are more difficult to design than digital circuits that accomplish the same task. It would take a designer who is familiar with analog circuits to design an analog radio receiver, or an analog battery charger, since digital components have been adopted to simplify those designs.
Analog signals are commonly used in communication systems that convey voice, data, image, signal, or video information using a continuous signal. There are two basic kinds of analog transmission, which are both based on how they adapt data to combine an input signal with a carrier signal. The two techniques are amplitude modulation and frequency modulation. Amplitude modulation (AM) adjusts the amplitude of the carrier signal. Frequency modulation (FM) adjusts the frequency of the carrier signal. Analog transmission may be achieved via many methods:
Much like the human body uses eyes and ears to capture sensory information, analog circuits use these methodologies to interface with the real world, and to accurately capture and process these signals in electronics.
Unlike analog circuits, most useful digital circuits are synchronous, meaning there is a reference clock to coordinate the operation of the circuit blocks, so they operate in a predictable manner. Analog electronics operate asynchronously, meaning they process the signal as it arrives at the input.
Most digital circuits use a digital processor to manipulate the data. This can be in the form of a simple microcontroller (MCU) or a more complex digital signal processor (DSP), which can filter and manipulate large streams of data such as video.
Digital signals are commonly used in communication systems where digital transmission can transfer data over point-to-point or point-to-multipoint transmission channels, such as copper wires, optical fibers, wireless communication media, storage media, or computer buses. The transferrable data is represented as an electromagnetic signal, such as a microwave, radio wave, electrical voltage, or infrared signal.
Many systems must process both analog and digital signals. It is common in many communications systems to use an analog signal, which acts as an interface for the transmission medium to transmit and receive information. These analog signals are converted to digital signals, which filter, process, and store the information.
Figure 5 shows a common architecture in which the RF analog front-end (AFE) consists of all analog blocks to amplify, filter, and gain the analog signal. Meanwhile, the digital signal processor (DSP) section filters and processes the information. To convert signals from the analog subsystem to the digital subsystem in the receive path (RX), an analog-to-digital converter (ADC) is used. To convert signals from the digital subsystem to the analog subsystem in the transmit path (TX), a digital-to-analog converter (DAC) is used.
A digital signal processor (DSP) is a specialized microprocessor chip that performs digital signal processing operations. DSPs are fabricated on MOSFET integrated circuit chips, and are widely used in audio signal processing, telecommunications, digital image processing, high-definition television products, common consumer electronic devices such as mobile phones, and in many other significant applications.
A DSP is used to measure, filter, or compress continuous real-world analog signals. Dedicated DSPs often have higher power efficiency, making them suitable in portable devices due to their power consumption constraints. A majority of general-purpose microprocessors are also able to execute digital signal processing algorithms.
A DAC provides the reverse operation. The DAC input is a binary stream of data from the digital subsystem, and it outputs a discrete value, which is approximated as an analog signal. As the resolution of the DAC increases, the output signal more closely approximates a true smooth and continuous analog signal (see Figure 7). There is usually a post filter in the analog signal chain to further smooth out the waveform.
As with most engineering topics, there are pros and cons for both analog and digital signals. The specific application, performance requirements, transmission medium, and operating environment can determine whether analog or digital signaling (or a combination) should be used.
Although many original communication systems used analog signaling (telephones), recent technologies use digital signals because of their advantages with noise immunity, encryption, bandwidth efficiency, and the ability to use repeaters for long-distance transmission. A few digital signal applications are listed below:
Analogue signals can take any value between the maximum and minimum determined by the power supply. Digital signals, on the other hand, have only two specific values which are usually referred to as ON and OFF or HIGH and LOW. It is always assumed that digital signals change from one state to another very (infinitely) quickly.
The amplitude of any regular symmetrical periodic signal is the maximum value of the signal measured from zero (either positive or negative). The term 'amplitude' is often applied to waves in Physics and is less common in Electronics. In Electronics we refer to the peak value and the RMS value. The diagram shows the peak and RMS voltages of a sinusoidal (like a sine wave) electrical signal.
Consider a periodic signal such as the sine wave shown or a regular square wave etc. The Period (T) is the time taken for one complete cycle (measured in seconds). The Frequency (f) is the number of cycles each second (measured in Hertz). The relationship between Frequency and Time Period is:Frequency = 1 Time Period
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As its name implies, the function of an analog-to-digital converter (ADC) is to convert analog signals to digital representations for processing by a microcontroller (MCU), field-programmable gate array (FPGA), digital signal processor (DSP), or similar device.
Regardless of how it accomplishes the task, an ADC produces a digital output from an analog input signal, a process known as quantization. Quantization error results from this process since a digital signal can only have discrete values, whereas an analog signal may have any value within the dynamic range of the signal.
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